Processing systems for manufacturing feed pellets for poultry and livestock are well known. Of increasing importance within this industry is the usage of liquid additives. These additives include amino acids, vitamins, flavors, mold inhibitors, pellet binders, antioxidants, drugs and enzymes. In some pellet processing systems, these liquid additives are applied as a coating to finished pellets prior to directing the pellet stream to a bin for storage. Typically, the pellets are provided either by gravity feed or motorized conveyor to a control gate which selectively opens to drop pellets through a spray chamber. The spray chamber is a volumetric structure typically having nozzles mounted along at least one wall of the spray chamber. These nozzles are coupled to pumps that provide liquid additives from a reservoir to the nozzles so the liquid additives are dispensed under pressure from the nozzles to coat the pellets as they fall through the spray chamber. The coated pellets typically fall into a hopper that has a motor-driven au mounted at its lowest end for transporting the coated pellets to a conveyor belt for routing to storage bins.
One of the problems with these types of systems is the need to periodically shut down the processing equipment and clean the spray chamber. The cleaning of the spray chamber is required because liquid additives, which miss pellets in the stream as they fall through the spray chamber, adhere to the wall opposing the nozzles of the spray chamber. Of course, the down-time associated with the cleaning of the spray chamber impacts the utilization of the pellet processing system and its economic efficiency. To extend the time between spray chamber cleanings, nozzles are typically placed at an angle on the high side of the spray chamber to reduce the likelihood that the spray has sufficient energy to reach the opposing wall if it passes through the pellet stream without contacting one or more pellets in the stream. A typically rule of thumb for placement of nozzles is the use of one nozzle for each two to three feet of spray chamber length. While careful placement of the nozzles somewhat increases the time between spray chamber cleanings, these cleanings are still required on a regular basis.
What is needed is a system that substantially reduces the need for spray chamber cleanings in a feed pellet processing system.